RNY Gastric Bypass Surgery Complications, Risks

Gastric bypass, referred to as Roux-en-Y, is a highly effective procedure for reducing morbidly obese patients who have a 35 or higher body mass index (BMI). It is also successful in improving obesity-related comorbidities like type 2 diabetes, cardiovascular disease, asthma, and sleep apnea.

Gastric Bypass Surgery Procedure

Undergoing gastric bypass weight loss surgery does carry a certain degree of risks just as any surgery would. Fortunately, most risks can be eliminated by following the pre-op diet and having a qualified surgeon.

The most common risks that occur include;

The learning curve for gastric bypass operation is steeper than lap band and gastric sleeve. The risk of gastric bypass complications is lower at centers like Mexico Bariatric Center that do hundreds of bariatric surgeries per year (SOURCE: WebMD and MBC Research Study).

Gastric Bypass Gone Wrong

The Roux-en-Y Gastric Bypass is a rather complex procedure requiring many small millimeter-sized incisions and attachments.

Surgeons must have proper technique and precision to minimize complications and risks. Sometimes, when the intestine is attached to the new stoma, the doctor can make the opening too big, causing too much food to ‘bypass through.’

According to West Penn Allegheny Health System, the mortality rate for gastric bypass is less than .03% (or 1 in 300 patients). In the United States, nearly 4 to 5% of patients who undergo gastric bypass will experience some kind of a complication (about 1 in 20 patients).

Post-Operative Risks and Complications

RNY Gastric Bypass Surgery Complications, Risks

The potential problems associated with gastric bypass surgery can be categorized as moderate to severe, both short and long term. Remember, it’s important to have a bariatric surgeon with enough surgical skill and experience to make the appropriate-sized connections.

Short-Term Risks and Complications (Immediate)

Immediate issues that arise after undergoing gastric bypass surgery are known as short-term complications. These short-term problems can be easier to detect with post-op tests and can be resolved quickly if you are still in the hospital/recovery.

Short-term complications after gastric bypass surgery may include;

  • Internal Bleeding
  • Adverse reactions to anesthesia or medications
  • Blood clots (Deep Vein Thrombosis and Pulmonary Embolus)
  • Collapsed lung or breathing problems
  • Leakage in your gastrointestinal system
  • Infection (bladder, skin, abdominal, wound, or urinary tract)
  • Heart attack
  • Stroke
  • Injury to the abdomen, internal organs, esophagus
  • Pneumonia

Long-Term Risks and Complications

Long-term complications that arise after gastric bypass are different because they usually go unnoticed for at least a few weeks post-op – sometimes much longer. These can be potentially risky because the signs and symptoms of complications may not be obvious or visible. You have to listen to your body and see your doctor before the problem escalates or becomes more serious.

Long-term risks and complications may include;

Common Risks and Complications


Gallstones will typically happen in as many in 33% of patients, according to Cleveland Clinic. Gallstones are small stones of cholesterol that cause serious pain as they pass, inflammation of the gallbladder, and lead to gallbladder removal. The risk for them rapidly increases with fast, substantial weight loss. Gallstones can be prevented by taking bile salts as a supplement for up to six months following surgery.


Ulceration commonly forms on the gastric side and the jejunal side of the gastrojejunal anastomosis. A marginal ulcer occurs in approximately 5% of RNY Gastric Bypass patients. The symptoms are often associated with pain, vomiting, nausea, food intolerance, and bleeding.

Complications, such as ulcers, can be managed endoscopically after gastrointestinal weight loss surgery. Smoking after gastric bypass leads to ulcers and perforations.

Hiatal Hernia

Perhaps the most common complication is a Hiatal hernia. The hiatus is the diaphragm opening or the muscle wall that separates the chest cavity itself from the abdomen. The proper digestive process involves food moving through the esophagus through the hiatus and into the stomach. However, when a hiatal hernia occurs, the stomach bulges up into the chest. There are two types of Hiatal hernias, paraesophageal or sliding. A paraesophageal hiatal hernia, a portion of the stomach squeezes through the hiatus. Most of the time this kind of hernia has no symptoms, and it can potentially shut off the blood supply.

It’s important that women avoid pregnancy for up to two years when their weight is more stabilized. This is because rapid weight loss can lead to nutritional deficiencies that can harm a developing fetus and the chance of a successful pregnancy.

Research studies show that patients after laparoscopic gastric bypass and mini-gastric bypass surgery should take high-protein food and drinks in combination with alcohol drinks and exercise to avoid a low hemoglobin (Hgb) level.

Side Effects of Gastric Bypass Surgery

Most of the side effects incur as a result of a patient’s diet. To avoid diarrhea, nausea, weakness, and vomiting side effects, patients should avoid these foods:

  • High-fat foods
  • High-sugar foods

Dumping Syndrome

One of the major unpleasant side effects, dumping syndrome or rapid gastric emptying is common in patients after gastric bypass. Rapid gastric emptying occurs when sugary food moves from your stomach into your small bowel too quickly.

Dumping syndrome is caused by eating sweets or other simple carbohydrates, dairy products (in some people), and alcohol. The body in an attempt to dilute the sugar will flood the intestines, which will cause dumping syndrome symptoms such as nausea, vomiting, diarrhea, weakness, anxiety,  flushing, etc.

Patients can minimize the occurrence by eating small meals and following dietary guidelines set by their physician/nutritionist. Dumping syndrome could be a useful mechanism for patients to know about their diet as the body would signal the wrong foods and drinks.


Dehydration is common and a serious side effect of gastric bypass. Because your new stomach is only 4 ounces, patients will need to consume water many times a day. Patients will need to consume 64 ounces per day. Patients need to look out for nausea, vomiting.

Difficulty Swallowing

Patients who eat too quickly, or by not chew their food enough can have problems swallowing. Avoid eating too fast.


Indigestion can result typically because of poor patient diet. By fixing your diet, patients can reverse indigestion.

Hair Loss

Every day we typically lose 75 to 100 hairs, but some patients will lose hair during rapid weight loss (sometimes in clumps that may be alarming, but is purely hormonal). Once you are getting near your weight goal, hair loss will slow. Hair loss may or may not happen, but it usually isn’t something to worry about unless your physician is concerned about malnutrition. Typically the hair will regrow once you’ve reached your weight loss goal.

If you’re worried about hair loss you can take hair supplements (purchased from a variety of shops, online and brick and mortar) to help combat the rate at which you lose hair:

  • Co-Enzyme Q/10: 25-50mg per day
  • Biotin: 300mcg per day
  • Flax Seed Oil: 1-2 grams per day, gel-tabs, oil, or sprinkles
  • Zinc: 50mg per day

Nutrient Deficiency After Gastric Bypass

Approximately 30% of gastric bypass patients will develop a nutritional deficiency such as metabolic bone disease, anemia (iron deficiency), or osteoporosis. These deficiencies can be avoided if the proper vitamins and minerals are consumed following surgery and daily. According to the University of California –San Francisco, a gastric bypass patient should take the following vitamins or supplements:

  1. A multivitamin that includes a minimum of 18 mg of iron, selenium, zinc, copper, and 400mcg of folic acid. Take two of these a day for at least three months following surgery, and then just one daily.
  2. Take 1,200 to 2,000 mg of calcium each day. To enhance the chance of absorption, take it in two or three doses throughout the day.
  3. Take 800-1,000 IUs of Vitamin D. Divide the dosage into two doses. Take it with the calcium supplement.
  4. Take 500 mcg of Vitamin B.

To reduce post-op deficiencies, all gastric bypass patients should consume nutritional supplements made according to ASMBS recommendations, such as Emerge Bariatrics Vitamins.

Guide to Gastric Bypass Surgery: